My preference is for a folder without a clip, mostly because I'm more concerned with how comfortable they are using for an extended period, than anything else, and I haven't had any folder with a clip that is as comfortable as the same design without one.
I also don't like having the folder attached to my clothing in a spot where its likely to get scratched, banged, dinged, and otherwise out in the open for folks to see.
That means I carry a folder one of three ways. One is just in the bottom of a pants pocket. Right now I've got a A.G.Russel Jess Horn model in a leather slip pouch in my right rear pocket for utilty chores. Not intended for fast access, just a comfortable spot to carry one all the time.
Another good carry spot is the watch pocket on a lot of the new jeans, since they are narrow and deep, and will conceal completely a 3" or so blade folder. If I do carry a small folder with a clip, I'll usually carry it in the watch pocket, out of the way.
Last carry option is a pouch. For larger folders, including ones I make myself, I much prefer that to a clip, and my favorite carry pouch is of the 'stealth' variety.....it came off the Gerber Multi-tool that is in my backpack! Its big enough, and there is enough adjustment to the velcro to fit a range of large folders, plus is slightly padded to protect the knife, with a soft liner.
Best of all, nobody wonders what you're carrying...just assuming you've got one of those belt workshops, like half of everyone else up here. Popping the velcro and pulling the folder is not a heck of a lot slower than pulling a knife with a clip.